A backlight unit, installed behind LCD which does not produce light itself, illuminates the LCD uniformly to produce a visible display image. A light guide plate is a component realizing brightness and uniform illumination of the backlight unit and passes light emitted from LEDs uniformly across the entire surface of the LCD.
FIG. 1 illustrates the structure of a backlight unit which makes use of the LED as a light source. As shown in the figure, the backlight unit has a plurality of LEDs 20 installed in an upper part of a printed circuit board 10 and has a light guide plate 30 delivering the light emitted from the LED 20 to the upper part. In particular, a plurality of LEDs are used for a light source and attempts are made to have the light emitting surface emit light uniformly across the entire surface. In this case, a plurality of LEDs are disposed on the surface and holes are formed on the light guide plate so that LEDs can be inserted inside the holes.
If LEDs are inserted into the inside the light guide plate, hot spots are generated due to the heat in the surface close to the LEDs. Because of this, the brightness of an area close to the LEDs becomes relatively high and accordingly, brightness specks are formed in that area.